Determining that printing a 3D object from a selected build material is expected to result in a defect

Abstract

A method includes receiving an object model describing a geometry of a three-dimensional, 3D, object for printing by a 3D printer, and build material data indicating a selected build material to be used in printing the 3D object by the 3D printer. A volume to surface area ratio of the object model is calculated. In response to the volume to surface area ratio being greater than a first predetermined threshold value for the selected build material, it is determined that printing the 3D object by the 3D printer from the selected build material is expected to result in a defect in the 3D object.

The invention claimed is: 
     
         1 . A method comprising:
 receiving, by a processor of a device, an object model describing a geometry of a three-dimensional (3D) object for printing by a 3D printer;   receiving, by the processor, build material data indicating a selected build material to be used in printing the 3D object by the 3D printer;   calculating, by the processor, a volume to surface area ratio of the object model;   in response to the volume to surface area ratio of the object model being greater than a first predetermined threshold value for the selected build material, and prior to printing of the 3D object being initiated, determining, by the processor, that printing of the 3D object by the 3D printer from the selected build material in accordance with the object model as received is expected to result in a defect in the 3D object.   
     
     
         2 . The method of  claim 1 , further comprising:
 in response to the volume to surface area being greater than the first predetermined threshold value, not initiating printing the 3D object with the 3D printer in accordance with the object model as received.   
     
     
         3 . The method of  claim 1 , further comprising:
 in response to the volume to surface area being greater than the first predetermined threshold value, displaying, by the processor, a warning message on a user interface indicating that printing of the 3D object by the 3D printer from the selected build material in accordance with the object model as received is expected to result in a defect in the 3D object.   
     
     
         4 . The method of  claim 1 , wherein the first predetermined threshold value has a value within a range between 1.5 mm 3 /mm 2  and 8 mm 3 /mm 2 , the range including 1.5 mm 3 /mm 2  and 8 mm 3 /mm 2 . 
     
     
         5 . The method of  claim 1 , further comprising:
 in response to the volume to surface area being greater than a second predetermined threshold value and less than or equal to the first predetermined threshold value, displaying, by the processor, a warning message on a user interface indicating the 3D object is at risk of failure.   
     
     
         6 . The method of  claim 1 , further comprising:
 In response to the volume to surface area ratio being greater than the first predetermined threshold, and prior to printing of the 3D object being initiated, modifying the object model to reduce the volume to surface area ratio.   
     
     
         7 . The method of  claim 1 , further comprising:
 calculating, by the processor, the volume to surface area ratio in response to receiving build material data indicating the selected build material has a shrinkage at crystallization of over 1.5% at a cooling rate of under 5° C. per minute.   
     
     
         8 . An apparatus comprising:
 a memory to store an object model describing a geometry of a three-dimensional (3D) object and build material data indicating a selected build material from which to form the 3D object; and   a processor to determine, prior to generation of the 3D object being initiated, whether the 3D object can be generated from the selected build material in accordance with the object model as received without causing upward expansion of the 3D object, by determining a volume to surface area ratio of the object model is less than a predetermined ratio.   
     
     
         9 . The apparatus of  claim 8 , wherein the apparatus is a 3D printing apparatus configured to generate the 3D object based on the object model in accordance with the object model as received, in response to the processor determining that the 3D object can be generated in accordance with the object model as received without causing upward expansion of the 3D object. 
     
     
         10 . The apparatus of  claim 8 , wherein the processor is further to transmit the 3D object model to a 3D printer for printing in accordance with the object model as received, in response to the processor determining that the 3D object model can be generated in accordance with the object model as received without causing upward expansion of the 3D object. 
     
     
         11 . The apparatus of  claim 8 , wherein the selected build material comprises polypropylene. 
     
     
         12 . The method of  claim 1 , wherein the predetermined ratio has a value within a range between 1.5 mm 3 /mm 2  and 8 mm 3 /mm 2 , the range including 1.5 mm 3 /mm 2  and 8 mm 3 /mm 2 . 
     
     
         13 . A non-transitory machine-readable storage medium storing instructions executable by a processor to perform processing comprising:
 calculating a volume to surface area ratio of a three-dimensional (3D) object model, the 3D object model describing a 3D object for printing the 3D object in a build chamber from a build material;   determining, prior to generation of the 3D object being initiated, whether generation of the 3D object from the build material in accordance with the object model as received is expected to result in upward expansion of the 3D object during generation, in a case where the volume to surface area ratio of the 3D object model is less than a predetermined ratio.   
     
     
         14 . The non-transitory machine-readable storage medium of  claim 13 , wherein the processing further comprises:
 modifying the 3D object model to include a cavity, in response to determining that generation of the 3D object in accordance with the object model as received is expected to result in upward expansion of the 3D object during generation.   
     
     
         15 . The non-transitory machine-readable storage medium of  claim 13 , wherein the processing further comprises:
 initiating generation of the 3D object in the build chamber from the build material, in response to determining that generation of the 3D object in accordance with the object model as received is not expected to result in upward expansion of the 3D object during generation.   
     
     
         16 . The method of  claim 1 , wherein the first threshold predetermined threshold value has a value within a range between 2.0 mm 3 /mm 2  and 7 mm 3 /mm 2 , the range including 2 mm 3 /mm 2  and 7 mm 3 /mm 2 . 
     
     
         17 . The method of  claim 2 , further comprising:
 in response to the volume to surface area being less than the first predetermined threshold value, initiating printing of the printing 3D object with the 3D printer in accordance with the object model as received.   
     
     
         18 . The method of  claim 1 , further comprising:
 in response to the volume to surface area being less than a second predetermined threshold value that is less than the first predetermined threshold value, initiating printing of the 3D object with the 3D printer in accordance with the object model as received.   
     
     
         19 . The method of  claim 18 , further comprising:
 in response to the volume to surface area being greater than the second predetermined threshold value and less than the first predetermined threshold value, not initiating printing of the 3D object with the 3D printer according to the object model with or without the object model having first been modified to reduce the volume to surface area ratio.   
     
     
         20 . The method of  claim 19 , further comprising:
 in response to the volume to surface area being greater than the first predetermined threshold value, not initiating printing of the 3D object with the 3D printer according to the object model without the object model having first been modified to reduce the volume to surface area ratio.